(a) Field of the Invention
The present invention relates generally to deployable structures, and specifically to systems for deploying umbrella-type reflectors for satellite antennae or similar satellite appendages.
(b) Description of Related Art
Deployment systems for satellite antennae reflectors such as umbrella-type reflectors typically include a hub mechanism for deployment. Such hub mechanisms typically include shafts, drive screws, hinges, linkages and mechanical stops, typically constructed of metallic materials. Such arrangements exhibit reduced thermal stability due to excessive coefficients of thermal expansion as well as a reduction of deployment repeatability. Known hub mechanisms are typically quite bulky (i.e., having a diameter of about ten percent of the overall reflector diameter) and rely on pyro-technic devices for initiating deployment. Such pyro-technic devices present safety and reliability problems and require additional electronics for the control and actuation thereof. Pyro-technic devices also require extensive design and testing efforts to ensure that the antenna reflector structure can withstand loads associated with "pyro shock" and the resulting dynamic deployment motion which is difficult to analyze and/or simulate in a 1-G deployment environment (i.e., in a ground-based test). Pyrotechnics also require refurbishment after each use.
In addition, known hub mechanisms do not typically generate sufficient torque to deploy a reflector in a 1-G environment (e.g., for ground-based testing and evaluation). As a result, large and complex off-loaders are required for ground-based operation and testing of such hub mechanisms and the reflectors on which they are installed.
Accordingly, there is a need for a deployment system for satellite appendages, such as umbrella-type reflectors, that is configured so as to minimize or eliminate the aforementioned problems.